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Computed fuel out of whack

WingedFrog

WingedFrog

Well Known Member
I got the PT60 fuel flow sensor and I have not been able to adjust it to match the real fuel consumption. Followed Dynon's instructions, went up to 96,000 pulse/Gal. still showing too much fuel burned. I dread having to return this red cube to Dynon, any idea?
 
If you have to go that far away from the recommended starting K factor of 68,000 then something is wrong...

Ideas to check:

  • Bad connections can cause this (check the factory crimps really good)
  • Check the install to be triple sure that it is installed correctly.
  • Ensure that it is not in a high vibration situation as this can also cause false high readings.
  • Ensure there is no way any air bubbles can get trapped in the cube

I also forgot that you RV12 builders have a return flow. I would follow BigJohn's advice on this post below.

I doubt there is anything wrong with your red cube....
 
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Go to this thread for a description of how I progressed through calibration in 2011. Read Post #17 for the technique I ended up with, which worked very well for me. For the next several flights after getting the initial value set I just tweaked the K factor as per Dynon suggestions. My fuel flow and fuel used readings are very trustworthy now, regardless of my cruise power settings.
 
Thank you guys, I will follow your advice.
One thought came up to my mind: as I have a high fuel pressure (required adjustment of the set-up values as documented on another thread) typically at the high end of green and sometimes in yellow, I am wondering if this is not resulting in a fuel return flow that cannot be compensated by calibration limited to 98,000 pulses per gallon?
 
Winged Frog,

Your best bet is to use the RETRN parameter to null out the return flow, then use the K factor to get an accurate flow value, as described in my post referenced above. Try it, what do you have to lose?

John
 
I'm at this stage and I am a little confused. My fuel flow calibration menu has two values (Skyview 10.0) and they refer to two electrical pin numbers. There isn't a RETRN value. An even through the manual tells you how to get to these, it doesn't say anything about what to set them to or how to modify them for the conditions. I must have missed something in the install guide because I couldn't find a word on it. It refers to a section called "Fuel Computer" but, you guessed it, there isn't a section called that.

Anyone else been through this on the new version of Skyview?
 
Try this page in Skyview install Manual.

Check page 7-62 in the Skyview installation Guide Rev Q. Labeled, "Fuel Computer Configuration". ;)
 
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